1. Field of the Invention
This invention relates to vacuum cleaners. In one of its aspects, the invention relates to a vacuum cleaner that includes a cyclone dirt separator. In another of its aspects, the invention relates to a vacuum cleaner that incorporates a cyclone separator in combination with a filter bag for dust collection.
2. State of the Prior Art
Upright vacuum cleaners include a handle mounted to a base for pivotal movement between an inclined use position and a generally vertical storage position. Such an upright vacuum cleaner is disclosed in U.S. Pat. No. 6,256,833 issued Jul. 10, 2001. The disclosed upright vacuum cleaner includes a suction nozzle in the base and an agitation brush in the suction nozzle, the suction nozzle being fluidly connected to a suction source and a filter bag enclosure mounted to the handle of the cleaner. Soil from a surface being cleaned is entrained in an airflow from the suction nozzle and transported to the filter bag enclosure for deposit in a semi-permeable filter bag, as is well known in the art. A filter bag is generally disposable, and requires frequent replacement when it becomes full. The effectiveness of some vacuum cleaners decreases prior to the filter bag becoming full, as fine particles trapped by the filter bag degrade its permeability and cause a loss of suction deliverable to the suction nozzle.
Vacuum cleaners using a cyclone separator have the advantage of not requiring replacement of the disposable, non-reusable, filter bag. However, in order to match the dirt capacity of a filter bag-type vacuum cleaner, the cyclone-type vacuum cleaner is usually fairly large to accommodate the generally cylindrical cyclone separation chamber. As the diameter of the cyclone chamber increases, the rotational velocity of the air decreases for a give size vacuum motor. This lower velocity adversely affects the efficiency of the cyclone separator. The large dirt reservoir is also cumbersome to handle while still requiring frequent emptying to avoid re-entrainment of collected dirt into the suction airstream. Decreasing the size of the cyclone chamber could increase its efficiency and ease of handling, but at the cost of further decreasing its capacity to hold dirt when compared to the filter bag-type cleaner.
U.S. Pat. No. 6,146,434 issued Nov. 14, 2000, to Scalfani et al. discloses a stick vacuum cleaner having a floor engaging base with a nozzle opening, a handle pivotally mounted to the base and including a working air conduit from the base to a dirt cup that has cyclonic action to separate entrained dust from the air, a filter bag that covers the outlet from the dirt cup and a suction source above the filter bag to draw the dirty air from the nozzle opening through the cyclonic dirt cup assembly and through the filter bag. The “stick” vacuum disclosed is limited by weight in the strength of suction motor it can accommodate.
PCT published patent application No. WO 84/02282 discloses a dust collector that includes a cyclone separator that communicates with a hose or flexible tubing with a suction nozzle at one end to separate coarse particles from the air. The outlet from the cyclone separator is connected to a bag filter for removing less coarse particles. A suction fan draws air through the cyclone separator and through the bag filter.
U.S. Pat. No. 6,195,835 discloses a canister vacuum cleaner in which a small cyclone dust-collecting device is mounted to a wand for separating and collecting dust and dirt of comparatively large particle size from the air that is then drawn through a conventional bag filter in a canister. A small dirt-collecting tub that is removably mounted biaxially alongside the wand forms the cyclone dust-collecting device.